<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			#box{
				list-style: none;
			}
		</style>
	</head>
	<body>
		<div >
			<h3 onclick="fun1()">我的电脑</h3>
			<ul id="box" >
				<li style="display: none;" id="first">music</li>
				<li style="display: none;" id="second">document</li>
			</ul>
		</div>
		<script>
			var n=1;
			    function fun1(){
			    	n++;
			    	if (n%2==0) {
			    		document.getElementById("first").style.display="block"
				        document.getElementById("second").style.display="block"
			    	}else{
			    		document.getElementById("first").style.display="none"
				        document.getElementById("second").style.display="none"
			    	}
			    	}
		</script>
	</body>
</html>
